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BRITAIN'S EXPORT AIRSHIP
altitude makes reliable and accurate height information
essential. A Bendix weather radar, is specified, and for
homing a transponder on the mast provides range and
bearing. Similarly, their relatively low speed can result in
very large drift angles, and some form Of drift-meter will
be fitted. For navigation Aerospace Developments will
offer a VLF (very low frequency) package based on Omega.
Maintenance of the ships will be farmed out to local
operators, and other work such as crew training, flight
operations and technical publications will also be placed
locally. The British airship company has proposed a design
for a servicing hangar, though good facilities already
exist in Trinidad only 400 miles away, a relic of the USN
airship days.
The flight-test programme will be based on some 60hr
flying. Originally 200hr had been estimated, but this has
been cut on consultation with Goodyear. The test schedule
is at present rather nebulous and will probably not be
finalised until just before trials begin. Apart from perform
ance (speed, rate of climb on static lift and under power,
simulation of "hot and high" with reduced helium volume,
and manoeuvrability) there will obviously be emphasis on
emergency procedures such as maximum descent rates and
engine-out performance. Smooth certification will depend
heavily on the expertise of Belotti, Aerospace Develop
ments' test pilot. In addition to his background with the
US Navy and Goodyear noted earlier, Belotti was also
involved with test-flying the Wiillenkemper airship in
Germany.
LEADING DATA: AEROSPACE DEVELOPMENTS TYPE 500
Length 164ft Maximum diameter 50ft Height overall 61 -5ft Max speed
62kt Fuel capacity 100 Imp gal Propulsion two Porsche three-litre six-
cylinder air-cooled petrol engines of 200 h.p. (max) each, 150 h.p. (normal
max cruise), 100-120 h.p. (normal cruise) Cruise speed 50kt Max rate of
climb (200 h.p. rating each engine) 2,340ft/min Payload (exclusive of two
crew and 100 Imp gal fuel) 2-56 tons (ISA, 2,000ft pressure height), 20 tons
(ISA, 6,000ft pressure height), 2-1 tons (ISA +30°C, 2,000ft pressure
height), 1 -6 tons (ISA +30°C, 6,000 ft pressure height) Range (10 per cent
reserves) 300 n.m. Ferry range (with re-ballasting stops, 10 per cent
reserves) 1,400 n.m. Patrol range (38kt) 600 n.m.
Airships may have a big part to play in South America,
where replacement for superannuated fixed-wing aircraft
can cost up to fifty times as much as the original equip
ment. Aerospace Developments estimates that transport-
airship operators could charge $2/ton-mile, a figure which
takes into account the money borrowed to purchase the
ships at 5 per cent interest over ten years, and insurance
premiums of ten per cent of cost price during the first year
of operation. South America has some of the richest
mineral and timber land in the world, and the economics
of exploitation depend largely on accessibility. The cost
of motorways is prohibitive in relation to the number of
people served, while the rivers (even where they are
navigable) are likewise limited. Natural resources more
than 20 miles from river or road, although capable of
returning perhaps 500 per cent on investment, are usually
not worth the cost of transportation.
The Aerospace airships will, of course, have nowhere
near the performance needed to transport bulk materials,
but their deployment in relatively large numbers as a
result of the Aerovision initiative, says Wood, could bring
about a climate of opinion favourable to the introduction of
larger vehicles.
Returning to the economics of the present airships, Wood
estimates the total operating cost of an Aerovision vehicle
at $300/hr, assuming an annual utilisation of 2,800hr. On
this basis, he says, a ship will show a 20 per cent profit on
advertising operations if it flies only 300hr/year. The
Goodyear ships chalk up about 800hr/year on fair-weather
publicity flights, and Wood says that the Aerovision ships
will initially fly 1,000-1,500hr. The potential outlet for
aerial advertising over Caracas and its suburbs is very
large, so there should be no difficulty in showing accept
able returns on advertising alone. Initial cost is £400,000
FLIGHT International, 15 January 1977
Dowty Rotol's ducted propulsor is a seven-blade variable-pitch fan unit
enclosed in an aerodynamic, acoustically lined duct. Its main advantage
over a ducted propeller are lower noise and the convenience offered by
the reverse-thrust facility. Aerospace tells Flight that the advantages far
outweigh the greater initial cost and mechanical complexity. In addition
to its probable adoption on the airship, the Dowty unit is to be flown for
the first time later this year on a modified Islander
and estimated contract value of 22 ships is £13 million.
Aerospace Developments reports interest by other
companies and countries Surinam, for example, is
exploring the possibilities of using airships for photo-
surveys in support of mineral-prospecting, and South
Africa is looking for economical maritime patrol air
craft. Most important of all, perhaps, are the potential
opportunities opening up around the coast of Britain, with
the country's future prosperity largely tied up in the form
of vast offshore oilfields, and with profitable fishing in
the new 200-mile zones.
The possibility of using airships to keep an eye on oil-
rigs has been discussed by Britain's Ministry of Defence
(incidentally reflecting the new level of credibility resulting
from the CAA's pioneering certification work). Protecting
these expensive, vulnerable and dispersed installations at
reasonable cost during a time of international tension
would be very difficult; at present maritime patrol aircraft
such as Nimrod are employed. Airships, says Wood, would
be ideal for surveillance; a military version of the Aero
vision ship, with a crew of five and carrying a dunking
sonar, could remain on station for 72hr, ready to summon
RAF or Royal Navy armed support if necessary. Their
relatively low transit speed of 60kt or so would be unim
portant owing to the proximity of the rigs to land and the
proportion of time spent on station compared with the
transit time. Many of these rigs lie in the newly instituted
200-mile fishing zones declared by Britain, so to some
extent airships could double up the duties.
The coastal-patrol niche was the last stronghold of the
previous generation of airships, and may provide the
opportunity for a large-scale reintroduction of these
vehicles. A few years ago America's Advanced Research
Projects Agency conducted a survey of long-endurance
maritime patrol aircraft, airships and surface vehicles such
as hydrofoils. It came to the conclusion that, if the deci
sion was taken to go for a completely new vehicle—not
an adaption of an existing type—the airship would be
superior. John Wood says that a maritime reconnaissance
version of the Aerovision ship, with dunking sonar and a
surface detection radar such as the Ferranti Seaspray,
could be bought for about .£700,000, and its operating cost,
compared with that of a Nimrod, would be perhaps an
order lower. Such a project would call for only a small
development programme. D